Action-at-a-distance force

Definition

An action-at-a-distance force is a force exerted by an object on another object that is not in physical contact with it, acting over a distance through space. Examples include gravitational, electromagnetic, and nuclear forces.

5 Must Know Facts For Your Next Test

1. Gravitational force is a prime example of an action-at-a-distance force.
2. Einstein's Theory of General Relativity describes gravity not as a force but as the curvature of spacetime caused by mass and energy.
3. Newton's Law of Universal Gravitation mathematically expresses gravitational force as $F = G \frac{m_1 m_2}{r^2}$.
4. Action-at-a-distance forces can act through the vacuum of space without any physical medium.
5. The concept contrasts with contact forces, which require physical interaction between objects.

Review Questions

• What is an example of an action-at-a-distance force?
• How does Einstein's Theory of General Relativity describe gravitational interactions differently from Newton's theory?
• Why are action-at-a-distance forces able to act through a vacuum?

Related terms

Gravitational Force:

A type of action-at-a-distance force where two masses attract each other with a force proportional to their masses and inversely proportional to the square of the distance between them.

General Relativity:

Einstein's theory describing gravity as the warping of spacetime by mass and energy, replacing the concept of gravitational force.

Newton's Law of Universal Gravitation:

$F = G \frac{m_1 m_2}{r^2}$; it quantifies the gravitational attraction between two masses.